A California woman has pleaded not guilty to what is believed to be the first traffic offence alleging a motorist was using Google's new computer-in-glasses invention.

The device, known as Google Glass, features a thumbnail-size transparent display above the right eye.

The technology will not be made widely available to the public until next year, but Cecilia Abadie was one of about 10,000 "explorers" who received the glasses earlier this year as part of a try-out.

Her case highlights several issues, including distracted driving, wearable technology that will one day become mainstream, and how laws often lag behind technological developments.

Abadie was stopped in October on suspicion of driving at 80mph in a 65mph zone on a San Diego freeway. The California Highway Patrol officer saw she was wearing Google Glass and added a citation usually given to people driving while a video or TV screen is on in the front of their vehicle.

Abadie, a software developer, denied both charges in San Diego traffic court.

Her lawyer William Concidine said she would tell a trial set for January that the glasses were not on when she was driving, but activated when she looked up at the policeman as he stood by her car window.

The device is designed to respond to a head tilt by waking itself up.

Mr Concidine also said the vehicle code listed in the prosecution applies to video screens in vehicles and is not relevant to mobile technology such as Google Glass.

Police declined to comment, but a t the time of Abadie's citation, the highway patrol said anything which took a driver's attention from the road was dangerous and should be discouraged.

The lightweight frames are equipped with a hidden camera and tiny display that responds to voice commands. The technology can be used to do things such as check email, learn background about something the wearer is looking at, or to get driving directions.

Legislators in at least three states - Delaware, New Jersey and West Virginia - have introduced bills that would specifically ban driving with Google Glass.

Chris Dale, a spokesman for the tech giant, said he was not aware of any other tickets issued for driving with Google Glass.

Google's website contains an advisory about using the headgear while driving, saying: "Read up and follow the law. Above all, even when you're following the law, don't hurt yourself or others by failing to pay attention to the road."